Successful long-term storage of videotape recordings has been determined to be possible with this invention. Videotape recorders are sophisticated, precision machines. A video recording is made with a magnetic head which is narrow (about as narrow as a human hair), and travels a mile a minute over a thin film of flexible polyester.
The tape is made up of components which are hygroscopic and absorb or lose moisture, depending upon the humidity and temperature. It has been established that tape handling on a videotape recorder is dependent on humidity and temperature. The ideal relative humidity for videotapes is between about 35-45 percent. Within this range a good tape and recorder will operate optimally. One-hundred percent relative humidity can never be tolerated. Any condensation of moisture on the tape surface will cause the tape to cling to the tape guiding surface. This is because the water destroys the air film between the tape and the guides; as a result, tape movement will stop and the tape damaged.
Temperatures above approximately 150 degrees Fahrenheit can cause permanent damage to the tape. For long term preservation, the ideal tape temperature is between about 65-70 degrees Fahrenheit.
Thus, tapes should never be kept in a hot, wet environment; long enough for moisture to accumulate on the tapes. Most commonly used video tapes use a polyester-urethane binder which deteriorates in a hot, wet environment through hydrolysis. The rate of deterioration depends on the type of binder system used, but if the binder is allowed to deteriorate to the point at which all of the ester molecules are consumed, the tape is permanently degraded.